Suppose I have the following table

x |
---|

1 |

2 |

3 |

4 |

5 |

6 |

7 |

8 |

I am trying to mutate `wanted`

, which will store the values of `x`

separated by comma. Note that `wanted`

can contain maximum three numbers (`wanted `

will have only one row if `x`

has three rows).

wanted |
---|

1, 2, 3 |

4, 5, 6 |

7, 8 |

```
library(dplyr)
# toy data
df <- tibble(x = 1:8)
```